Why Do We Get Carsick or Seasick?

Deep in each ear is a place that helps us keep our balance. Cars and boats mix these places up so that they don't work, and we feel sick. Two organs in the inner ear keep us balanced. The semicircular canal, three tubes that connect to the vestibule, is sensitive to changes in movement and direction. Changes in the tilt of the angle of the body are sensed by the vestibule. Irregular motions can disturb the normal functions of these organs and might result in one of the various forms of motion sickness. Boats and autos often bounce up and down or go from one side to the other. Those motions upset our balancing systems, and then we get sick. Sailors ride on boats all the time, so the balancing system in their ears gets used to the motion of the boat. That's why they do not get seasick.